The present invention relates to techniques for driving dampers for a musical instrument (typically a keyboard musical instrument) and more particularly to a technique for processing data related to dampers.
Damper mechanisms for damping vibration of strings in a piano have been known, and normally, dampers are driven in response to damper pedal operation performed by a human player (or user). In pianos equipped with an automatic performance function, on the other hand, dampers can be automatically driven by an actuator. One example of such an automatic damper drive device is disclosed in Japanese Patent Application Laid-open Publication No. 2002-14669. In the automatic damper drive device disclosed in the No. 2002-14669 publication, an electromagnetic solenoid (actuator) is disposed at a position spaced a considerable distance laterally from a lifting rail provided for collectively or integrally moving a plurality of dampers, and in such a manner that a plunger of the electromagnetic solenoid is driven downwardly. The electromagnetic solenoid is also constructed in such a manner that the plunger downwardly abuts against one end of a loud lever supported at a pivot point and a lifting rod abuts against the upper surface, opposite from the pivot point, of the loud lever. As the electromagnetic solenoid is energized to downwardly depress the plunger, the one end of the loud lever descends or moves downward, so that the loud lever pivots about the pivot point to push upwardly the lifting rod. As the lifting rod is pushed upward like this, the lifting rail contacting the upper end of the lifting rod is pushed upward. In this manner, the dampers are moved out of contact with strings so that the strings will vibrate long (damper-off mode). Further, in the prior art construction, a lever returning spring is provided in association with the loud lever, and this lever returning spring normally urges or biases the loud lever in a direction opposite from the direction in which the lifting rod is pushed upward. Thus, once the energization of the electromagnetic solenoid is terminated, the loud lever returns to its original position by the biasing force of the lever return spring so that the dampers press against the strings (damper-on mode).
With the aforementioned prior art technique, the dampers are automatically drivable by the actuator (electromagnetic solenoid). However, because the loud lever is driven by the actuator (electromagnetic solenoid), the actuator (electromagnetic solenoid) has to drive the loud lever against the biasing force of the lever return spring provided in association with the loud lever, which would impose a great load on the actuator (electromagnetic solenoid).
Japanese Patent Application Laid-open Publication No. 2005-250120 too discloses a player piano where dampers are driven by an actuator. The player piano disclosed in the No. 2005-250120 publication includes a position sensor for detecting a depressed position of a loud pedal (i.e., damper pedal), and a solenoid for driving the loud pedal. The solenoid has a plunger connected to the loud pedal, and the position of the dampers is controlled by driving the solenoid through servo control using performance data of a MIDI (Musical Instrument Digital Interface) format and a result of the detection of the position sensor.
In such player pianos, a mechanism for transmitting motion of the loud pedal to dampers comprises a plurality of component parts disposed between the loud pedal (damper pedal) to the dampers, and the dampers are ultimately displaced or moved by the plurality of component parts changing a force transmitting direction and amount of displacement. Because the operating position of the dampers changes in response to user's depressing operation of the loud pedal, detection of a depressed position of the loud pedal can be said to be indirect detection of an operating position of the dampers. However, because the loud pedal and the dampers differ from each other in amount of physical displacement (i.e., physical displacement amount) and because some allowance exists between some of adjoining component parts within a force transmission route, it is difficult to accurately detect a position of the dampers by detecting a depressed position of the loud pedal (i.e., damper pedal). Thus, when the dampers (damper pedal) are to be automatically moved in accordance with performance data, there is a need to perform accurate positioning control of the loud pedal taking into account the aforementioned allowance and displacement amount difference (transmission error), which would make it difficult to accurately control the operating position of the dampers.